Organizations such as on-line retailers, Internet service providers, search providers, financial institutions, universities, and other computing-intensive organizations often conduct computer operations from large scale computing facilities. Such computing facilities house and accommodate a large amount of server, network, and computer equipment to process, store, and exchange data as needed to carry out an organization's operations. Typically, a computer room of a computing facility includes many server racks. Each server rack, in turn, includes many servers and associated computer equipment.
Because the computer room of a computing facility may contain a large number of servers, a large amount of electrical power may be required to operate the facility. In addition, the electrical power is distributed to a large number of locations spread throughout the computer room (e.g., many racks spaced from one another, and many servers in each rack). Usually, a facility receives a power feed at a relatively high voltage. This power feed is stepped down to a lower voltage (e.g., 110V). A network of cabling, bus bars, power connectors, and power distribution units, is used to deliver the power at the lower voltage to numerous specific components in the facility.
In some computer systems, one or more rack-level power distribution units are provided in a rack to distribute electrical power to the many servers in the rack. Each of the rack-level power distribution units may include a case with a large number of receptacles, each of which may be used to supply power to a different server, and a built-in input power cable that passes out of the case. Rack-level power distribution units may be attached to one or both interior sides of the rack near one end of the rack.
In some facilities, power is supplied to racks either through the tops of the racks or the bottoms of the racks. For example, power may be fed through the bottom of a rack from floor power distribution units or power panels under a false floor in a room of the data center. In some cases, rack PDUs are pre-installed in rack before the rack is placed in the data center. If the input power cable for the rack PDU is oriented in the wrong direction (for example, extending from the top of the rack PDU of a data center where power is fed from the bottoms of the racks), routing and cable management may be significantly more difficult (for example, longer cable runs, more cable bends, and more crossing/interweaving of input cables with other cables). In some cases, the rack PDU may be removed and the orientation reversed (inverting top with bottom, for example) to improve routing. Removing and reorienting rack PDUs may, however, be laborious (and thus add to installation costs), especially if the process must be repeated for many racks.
From time to time, rack PDUs operating in a data center may fail and need to be replaced. Removing a rack PDU may involve disconnecting a power input cable from a power source and feeding the power input cable into the rack (for example, through the bottom of the rack and false floor). Installing the replacement rack PDU may involve feeding the new power input cable back through and connecting to the power source.
Primary power systems for computer systems in operation typically need to be maintained or reconfigured from time to time. Some data centers, for example, have “single threaded” distribution via the electrical power supply to the floor and/or to the rack, and in which maintenance can only be performed when the components using power in the data center, such as servers, are shut-off. The down-time associated with maintenance and reconfiguration of primary power systems in a data center may result in a significant loss in computing resources. In some critical systems such as hospital equipment and security systems, down-time may result in significant disruption and, in some cases, adversely affect health and safety.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include,” “including,” and “includes” mean including, but not limited to.